Method and Apparatus for Borehole Sensing

ABSTRACT

The present invention provides an apparatus and method for sensing subsurface data. One embodiment of the invention comprises a shuttle attached to a conveyance where the conveyance and shuttle are adapted to be spooled downhole into a borehole for sensing seismic data. The shuttle contains a sensor package that is preferably acoustically isolated in the shuttle. The sensor package includes a sensor array and a magnet clamp. A sensor section can contain several shuttles, each shuttle containing at least one sensor. In one embodiment, the sensor can be a fiber optic sensor. The magnet clamp is operable to controllably clamp and acoustically couple together the sensor package, the shuttle, and the adjacent structure which is typically the borehole casing. The magnet clamp is likewise operable to unclamp and uncouple the shuttle from the adjacent structure so as to be retracted uphole for subsequent use.

FIELD

This is a division of U.S. patent application Ser. No. 10/104,320, filedMar. 22, 2002.

This invention is related to development of acoustic sensorsconfigurations and methods for efficiently recording subsurface seismicdata and more particularly to utilization of acoustic sensors forrecording borehole seismic data.

BACKGROUND

Borehole seismic data can be utilized to refine surface seismic dataprior to drilling production wellbores. Borehole seismic data canfurther be gathered on a continuing or recurrent basis to monitorsubsurface formations and reservoirs during production of the well. Thegathering of data on a continuing basis will assist in optimizingextraction of gas or oil deposits.

Borehole seismic surveys are conducted by placing the receivers in theborehole and operating a seismic source at the surface to generate anacoustic wave. Typically the receivers are placed in a shuttle anddeployed downhole for the duration of the survey and then removed. Theamount of information that can be obtained in borehole seismic surveyscan be limited by the logistics of deploying the shuttles downhole.

It is known for acoustic sensors or receivers to be permanently deployeddownhole to continuously monitor seismic data during production of awell. The sensors are typically deployed with a monitoring tool thatextends downhole and is integrally attached to the borehole casing. Theattachment means is typically a mechanical surface force clamping deviceand the sensors are typically housed in a side passageway or lateralextending section associated with the sensor housing or productiontubing which is laterally displaced from the primary flow passagewaythrough the production tubing. See, for example, U.S. Pat. No. 6,253,848issued Jul. 3, 2001 to Reimers et al. The permanent deploymentmonitoring tooling such as that taught in Reimers et al, cannottypically be retrieved or removed without destroying the wellborerendering the tool and sensors unusable for future borehole seismicoperations.

Many monitoring tools for permanently deploying seismic sensor arraysdownhole are single level monitoring tools. However, due to the complexsubsurface formation and strata and the various levels of the multipleproduction zones and reservoirs, multilevel monitoring tools are alsorequired to monitor various levels simultaneously. The monitoring toolthat deploys the sensor arrays will typically include a plurality ofsensor housings or shuttles where each shuttle contains at least onesensor. While a plurality of shuttles is desirable, an excessive numberof shuttles can result in an overly complex tool that is very large anddifficult to deploy. The total number of shuttles is typicallyeventually limited by the general power consumption requirements of thedownhole sensor, telemetry and clamping system. In general, a tool basedon the general tool architecture as outlined above can quickly becomelarge and complex when trying to increase the number of shuttles,resulting in system that is both expensive and difficult to deploy. Dueto system cost and high lost-in-hole risks, it can be impractical todeploy such a system permanently in a well. The number of shuttles isalso limited due to power consumption requirements, costs and difficultyof deployment. Known borehole tools, including those utilizing fiberoptic sensors, designed for permanently deploying sensor arraystypically include a surface force clamp attachment means for attachingthe sensor arrays to the borehole casing. This type of attachment meansresults in a monitoring tool that is not retractable or reusable at adifferent site. A borehole sensing apparatus that is not easilyremovably deployed into a borehole and which cannot be retrieved andreused in other boreholes is a problem that exists.

Similarly in the area of borehole logging, the number of transmittersand receivers and the distance between transmitters and receivers hasbeen increasing to improve the ability to detect formationcharacteristics in the undisturbed formation farther from the borehole.One method to get deeper penetration is to increase the distance betweensource and receivers, such that the receivers are detecting signals thatare returned from further distances in the borehole. A problem withincreasing the distance between sources and receivers is that increasingtool size can result in increasing difficulties in deployment, longerperiods of time required for logging, longer down-time for the well, andhigher costs. There is a need for expanding the distance betweenacoustic sources and receivers, or utilizing additional receiverswithout increasing tool size.

The use of a magnetic clamping device as a method of attachment can alsooptionally be utilized to attach the sensors. However, the ability tomagnetically clamp and unclamp the sensor downhole or at the well headdoes not resolve all retrieval problems because many times the tool,specifically the weight or main electronics cartridge, gets stuckdownhole. Magnetic clamping alone will not address the issue of thestuck tool.

Accordingly, the present invention is operable to overcome one or moreof the problems as set forth above.

BRIEF SUMMARY OF INVENTION

One embodiment of the invention is an apparatus and a method ofremovably deploying the sensor arrays comprising the steps of extendinga coiled tube, or other suitable conveyance such as a cable line, wireline or slickline downhole into a survey borehole where the coiled tubeor other suitable conveyance comprises a plurality of shuttles attachedthereto and where the shuttles include seismic sensor systems and amagnetic clamp in a non-magnetic clamping state, and then magneticallyclamping the shuttle to the borehole casing. The method can also includethe steps of magnetically unclamping the plurality of shuttles andretracting the deployment mechanism removing the shuttles from theborehole. The method can also include steps of magnetically unclampingthe plurality of shuttles, repositioning the shuttles in the borehole,and reclamping the shuttles. Any of the steps of deploying, clamping,repositioning, reclamping and can be controllably executed at thesurface.

Also, as noted above, a magnet clamp is utilized to couple the shuttleto the borehole casing. The magnet clamp is more compact compared totypical mechanical surface force clamping devices utilized in theindustry because it does not involve engagement of or movement ofmechanical parts exposed outside shuttle. Also, the magnet clamp doesnot have to be positioned in a side passageway away from the primaryflow passageway of the well and its use eliminates the need formechanical anchoring arms thereby further reducing the shuttle size. Oneembodiment of the magnet clamp comprises a surface hydraulic actuatorcontrol system adapted to hydraulically control a downhole actuator forpositioning of a magnet to engage or disengage the shuttle Electricalactuator control systems can likewise be used. The magnetic clamp is aclear improvement over the typical mechanical surface force clampingbecause the seismic sensor system can be retracted and utilized indifferent boreholes. However, as indicated above the magnet clamp doesnot address the issue of a stuck tool.

Another embodiment can comprise a conveyance having a sensor sectionwhere the various sensors are attached and a weak point in theconveyance below the small outer diameter sensor section and where thelarger outer diameter main electronics cartridges, weights or otherlarger components are attached to the conveyance below the weak point.This embodiment facilitates fishing a stuck tool and if necessarybreaking away the upper portion of the conveyance at the weak point.

Another embodiment of the invention incorporates bow springs with theshuttle for facilitating coupling and decoupling of the sensor. The bowspring can be adapted to extend the shuttle away from the conveyancetoward the borehole casing and retract the shuttle against theconveyance.

One embodiment utilizes hydraulic power to control the position of themagnet clamp in lieu of electrical power. In this embodiment, thehydraulic pressure from the surface positions an actuator which controlsthe position of the magnet for clamping and unclamping. The wire lineand the plurality of shuttles can be spooled downhole either in anunclamped state or a clamped state. In permanent monitoringapplications, the magnet clamp can be activated because in suchsituations hydraulic activation or deactivation would not be required.For permanent monitoring applications, the magnets can be spooled in anactivated state and deployed directly into the well bore as the wellbore is established.

One embodiment of the present invention is an apparatus and method thatutilizes the benefits of fiber optic communication and sensor systemscombined with a plurality of shuttle devices attached along a coiledtubing, or a cable line, wire line, slickline, or other suitabledownhole deployment means. The shuttle provides a housing for thesensors and each shuttle has a magnetic coupling clamp which enables thepresent invention to effectively and removably deploy or spool seismicsensor arrays downhole into a survey borehole for recording multi-levelthree-dimensional borehole seismic data. The borehole monitoring ordeployment tool comprises a coiled tubing, or a cable line, wire line,slickline or other suitable conveyance for extending a plurality ofshuttle devices containing fiber optic seismic sensors where the shuttledevices have a magnetic coupling clamp controllably operable to fixedlyengage and acoustically couple the shuttle to the borehole casing. Themagnetic clamp is further controllably operable to disengage anduncouple the shuttle from the borehole casing.

When the present invention utilizes fiber optic sensor systems, itbenefits from many advantages offered by fiber optic systems. Forexample, fiber optic systems can operate passively and thereforedownhole electronics and associated power from the surface to operatethe downhole electronics are not required. The ability to eliminatedownhole electronics improves reliability of the downhole sensor systemparticularly in higher temperature environments. The electronicsnecessary for operating the sensor arrays can be located at the surfaceand since the surface electronics can be relatively expensive, they canbe shared with other wells and utilized for multiple downhole fiberoptic sensor systems. Also, fiber optic technology allows for a smallerprofile and lighter weight system. Still further, all of thesecapabilities are advantageous for acoustic and seismic imagingapplications which require a large sensor array with high datatransmission capabilities. In this regard, fiber optic sensors can alsosupport multi-functional measurements through the fiber optic line. Thisfeature has great advantage in wire line or cable line applications aswell as production and formation monitoring sensor systems.

A further embodiment of the present invention comprises a method ofcalibrating a borehole sensing system including providing a fiber opticsensor section on a conveyance system comprising a fiber opticcommunication fiber, where the sensors are communicably linked andacoustically coupled to a transducer and conveyance system comprises atleast one fiber optic communication fiber; communicably linking thefiber to an optical electronics converter and communicably linking saidoptical electronics converter to said transducer, introducing a opticalsignal into the communication fiber, activating the transducers throughdetection of said optical signal by said fiber optic sensors, excitingsaid fiber optic sensors by activation of transducers, measuringresponse of the sensors, determining expected response of the sensorsbased on input optical signal; and comparing measured response toexpected response of said fiber optic sensors.

The above discussed features of the present invention as well as otherfeatures and advantages will be described further in the followingdetailed description of the drawings and will be appreciated by andunderstood by those skilled in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, reference may bemade to the accompanying drawings in which:

FIG. 1 is a diagrammatic view depicting a typical well site with arepresentation of a cross section of the subsurface formations with aborehole extending therethrough;

FIG. 2 is an enlarged diagrammatic view of a cutaway from a portion ofthe borehole revealing the cable line extending therethrough and theshuttle attached thereto;

FIG. 3 is a cross section of a shuttle revealing the borehole sensorsand the magnet clamp;

FIG. 4A is a cross section of the magnet clamp showing the hydraulicactuator and the magnet element in the clamp position;

FIG. 4B is a cross section of the magnet clamp showing the hydraulicactuator and the magnet element in the unclamped position;

FIG. 5 is a representative schematic of a downhole arrangement showingthe use of a fiber optic sensor;

FIG. 6 is a functional diagram of the borehole seismic sensing system;

FIG. 7, 7 a and 7 b is a tubing conveying tool with a bow spring toshuttle interface;

FIGS. 8 and 8 a show a bow spring shuttle and wire line conveyance;

FIGS. 9 and 9 a show a shuttle embedded in the wire line with bow springto sensor package interface; and

FIG. 10 is a wire line system view showing fishing head.

DETAILED DESCRIPTION OF INVENTION

The present invention provides an apparatus and method for removablydeploying seismic sensor arrays down a borehole or wellbore forefficiently recording subsurface seismic data. The apparatus is designedsuch that a plurality of seismic sensors or seismic sensor arrays can bedeployed down a wellbore by spooling down a plurality of seismic sensorsattached to a wire line (cable line), slickline, coiled tubing or othersuitable deployment mechanism. For purposes of this disclosure, when anyone of the terms wire line, cable line, slickline or coiled tubing orconveyance is used it is understood that any of the above-referenceddeployment means, or any other suitable equivalent means, may be usedwith the present invention without departing from the spirit and scopeof the present invention. One embodiment of the apparatus is designedwith a plurality of shuttle containers or simply shuttles, each shuttlecontaining a sensor array with the shuttles being attached along thewire line, coiled tubing or other deployment mechanism. The apparatus isadapted to lower or spool the wire line down the borehole then actuate amagnetic clamp integral with the shuttle to magnetically clamp andacoustically couple the sensors to the borehole casing. The apparatus isfurther adapted to deactuate the magnetic clamp, thereby unclamping theshuttle and sensors from the borehole casing. The apparatus is furtheradapted to retract the wire line and the plurality of shuttles andsensors attached thereto. The extending or retracting of the wire lineor cable line can be accomplished by a spooling mechanism.

One embodiment of the invention entails the deployment of a plurality ofshuttle devices having sensor arrays downhole into a well bore and thenactuating a magnetic clamp, or simply magnetically clamping andacoustically coupling the shuttle to the borehole casing.

One embodiment of the invention comprises a sensor package whichincludes the borehole sensors and the magnet clamp as one integral unitor sensor package. With this embodiment, clamping results in the sensorpackage being clamped against the wall of the shuttle and the entireshuttle then being clamped against the borehole casing. This results inacoustic coupling between the sensor package, shuttle and casing. Pleasenote however that one embodiment of the invention can comprise a sensorpackage designed to be already acoustically coupled to the shuttlewithout magnetic clamping whereby the magnet clamp only needs to clampthe shuttle to the borehole casing or any other adjacent structure. Thisembodiment is not shown in the drawing but would be clear to one ofordinary skill and is well within the scope of this invention. Once theborehole data has been gathered, the apparatus is operable such that themagnet clamps can be deactuated such that extracting the sensor arrayscan be performed.

An alternative embodiment of a conveyance tool comprises a coiled tubingas a method of conveyance and a shuttle attached thereto by a bowspring. When the coiled tubing is deployed, the bow spring can becollapsed against the tubing such that the shuttle attached thereto willbe held against the exterior of the tubing. A magnet attached on theexterior of the tubing an aligned with the magnet clamp is designed tofacilitate holding the shuttle against the tubing. When the coiledtubing tool is deployed to the appropriate depth or position, the bowspring tension can be released thereby extending the shuttle outwardfrom the tubing toward the borehole casing. This configuration isadapted to further facilitate coupling the shuttle to the boreholecasing.

Another embodiment of a shuttle having a magnetic clamping devicecomprises a wire line conveyance with a two-part shuttle attachedthereto. The two-part shuttle comprises an exterior cradle shuttleportion and a main sensor shuttle portion attached thereto by a bowspring. The main sensor shuttle portion contains the sensing devicessimilar to the shuttle described in FIGS. 2 through 4. When the bowspring is collapsed within the exterior cradle shuttle portion, the mainsensor shuttle portion is cradled therein. When the tension of the bowspring is released, the main sensor shuttle extends outward from theexterior cradle shuttle portion. This embodiment also furtherfacilitates coupling the shuttle to the borehole casing.

Yet another embodiment of a conveyance tool for the present inventioncomprises a shuttle embedded in a wire line conveyance. The shuttle isdesigned to be embedded in the wire line such that the outer diameter ofthe shuttle is approximately the same as the diameter of the wire lineconveyance. The shuttle again is a two-part device comprising anexterior cradle shuttle portion and a main sensor shuttle portionattached thereto by a bow spring. As described above, the bow springinterface is designed to retract and extend the main sensor shuttleportion.

Another embodiment comprises a borehole sensing system have a breakawaysystem. The breakaway system is designed such that the conveyance has asensor section where the sensors are attached and the conveyance has itsweakest point at the base of the sensor section such that the conveyancecould be broken at that weakest point to recover the upper portion ofthe tool including the sensor section while leaving the portion of thetool below the breakaway point for later retrieval. A further embodimentprovides a tension-sensing device to sense tension in the conveyance.Such a breakaway system may be incorporated into any of the embodimentsabove.

Another embodiment comprises a method for obtaining geophysicalinformation about subsurface formations comprising deploying a shuttle,having a sensor package therein in a borehole for sensing data where thesensor package has a magnet clamp operable to selectively magneticallyclamp the shuttle to an adjacent structure is attached to a conveyance;selectively clamping said shuttle to the adjacent structure with saidmagnet clamp acoustically coupling together the sensor package, theshuttle, and the adjacent structure; deploying an acoustic source intothe borehole; generating an acoustic signal in the borehole; and sensingborehole data with said sensor package. A particular embodimentcomprises deploying an acoustic source disposed in a sonic tool into theborehole.

Referring to FIG. 1, a diagrammatic view of a well site is shown with adiagrammatic representation of a cross section of the subsurfaceformations with a borehole extending therethrough. The diagrammatic view100 depicts well instrumentation 102 at the surface including allassociated instrumentation and monitoring systems. Also shown at thesurface is a surface source 104 which is depicted as a vibrationvehicle. Alternatively, the source 104 may be an acoustic sourcedeployed into the borehole 110 for generating an acoustic signal in theborehole. The plurality of lines 106 are intended to representexcitations or seismic vibrations traveling through the subsurfaceformations producing seismic data that can be sensed by downhole sensorarrays. The present invention can be utilized to record seismic data forconducting a seismic survey of the subsurface formations 108. Thepresent invention can also be utilized to control and monitor operationsduring production by monitoring seismic data from the various subsurfaceformations, regions, and zones. In the monitoring capacity, the presentinvention can be utilized to optimize production of the well. Theplacement of the well bore 110 can be strategically located based onknown seismic survey data that may have been previously obtained.Optimal placement of the well bore is desired such that optimalrecording of seismic data for the subsurface formations of interest canbe obtained.

Once the well bore has been established, a wire line (cable line) 112, acoiled tubing or other conveyance can be spooled to extend down throughthe well bore where the plurality of sensor arrays are positioned alongthe wire line 112. Also, note that the wire line with the seismicsensors attached thereto can be extended as the well bore is beingestablished. The present invention can be either permanently deployedfor continuous production well monitoring or can be temporarily deployedfor performing a subsurface seismic survey and then retracted. If thepresent invention is temporarily deployed, it can be reutilized in asubsequent well bore operation once it has been retrieved. This featureprovides a great advantage over other systems presently available. Ifthe present invention is permanently deployed it can continuouslymonitor production well operations. Once the wire line and the pluralityof sensor arrays are in position, seismic data can begin to be gathered.If production ceases at the well or for some other reason seismicmonitoring is no longer required, the system can be retracted andreutilized elsewhere. Note that the diagrammatic illustrations presentedherein to describe the present invention are for the purpose ofillustration and ease of understanding the apparatus and methods of thepresent invention. The diagrammatic illustrations shown and describedherein should not be construed to be limiting in any way with respect tothe scope of the present invention.

Referring to FIG. 2, a diagrammatic view of a cutaway from a portion ofthe borehole casing is shown with the cable line or wire line extendingtherethrough having a shuttle attached thereto. In this view, a portionof the borehole casing 202 is shown with a sectional cutaway revealingthe wire line 112 and a shuttle carrier 204 attached thereto. The wireline with the shuttle attached thereto can be spooled to extend downthrough the borehole as indicated by arrows 206. A shuttle 204 houses aborehole sensor array and a magnetic clamping device utilized toacoustically couple the shuttle and sensors to the borehole casing. Thewire line 112 can include at least one communication line and caninclude at least one hydraulic pressure line. One embodiment of thecommunication line can be fiber optic to interface with a fiber opticacoustic sensor device for uphole transmission of seismic data. Thehydraulic line can be any appropriate actuator line, electronic orotherwise, that is adapted to actuate the magnetic clamp.

Referring to FIG. 3, a cross section of a shuttle revealing the boreholesensors and the magnetic clamp is shown. The shuttle carrier 204 isattached to the wire line 112. Internal to the shuttle housing is a finewire suspension 302 which is part of an acoustic isolator 304 whichacoustically isolates the sensor package 308 from the shuttle 204. Theshuttle and sensor package is designed to be mechanically reliable andacoustically robust to isolate the sensor package from the dynamics ofthe wire line or cable line 112 and to insure independent seismicrecording at each shuttle and sensor package. The acoustic isolationsystem includes a fine wire suspension line 302 integral with anacoustic isolator which acts as a suspension spring with a high dampingfactor between the carrier (shuttle) and the sensor package 308. In oneembodiment, the acoustic isolator 304 can be three quad rings attachedto the fine wire suspension that in combination act as a suspensionspring. One example of fine wire suspension is fine wire rope. However,the acoustic isolator can be any appropriate suspension spring-typemechanism. The acoustic isolation system is designed such that themotion of each sensor package becomes independent and is protected fromthe noise transmitted through the wire line 112. This allows seismicsignals to be acquired without interference from any dynamics of theshuttle carrier 204 and the wire line 112. Also, by separating the heavypart of the shuttle from the sensor part, the ratio of the clampingforce to the moving mass increases. This provides better couplingconditions between the sensor package and shuttle combination and thecasing. Also, when the wire line and shuttle is dragged upward, the finewire suspension pulls up the sensor package. With the magnetic damper306 on, the fine wire suspension allows the sensor package to alignwith, and at the same time, be in fall contact with the borehole casing,thereby establishing a good coupling condition during the dragoperation. The drag operation can be utilized when an undesired rockingmotion is occurring. Rocking motion occurs when the sensor package hasnot established good contact. The sensor package under these conditionswill begin a seesaw motion. A solution to this problem is to perform thedrag upward operation to establish a stable contact. Although it isgenerally preferred to use the above described acoustic isolationsystem, it is also recognized and anticipated that the sensor packagecan be acoustically coupled to the shuttle through a wide variety ofother means including being permanently affixed to the interior of theshuttle prior to being deployed downhole.

One embodiment of the invention utilizes fiber optic geophones as theborehole sensors for converting present seismic waves intoelectro-optical signals that can be transmitted across fiber opticcommunication lines. For this embodiment of the invention, fiber opticcommunication lines will be utilized in the cable line for transmittingseismic data uphole.

The same sensor package devices can be utilized for both the non-bowspring configurations shown in FIGS. 2 through 4 and the bow springconfigurations shown in FIGS. 7 through 9 to be discussed below. Also,one embodiment of the present invention can be designed such that thesensors provide triaxial capability or three-dimensional capabilitywhereby each shuttle comprises a sensor array of at least three mutuallyorthogonal geophones which are fixed relative to the sensor packagegeometry. In another embodiment, each shuttle comprises a hydrophone.Each of the shuttle and sensor packages that are installed along thewire line will monitor and record seismic activity at its respectivedepth.

Referring to FIGS. 4A and 4B, a schematical representation of the damperis shown in both its actuated damper on position, FIG. 4A, and itsdeactuated damper off position, FIG. 4B. Also shown in FIGS. 4A and 4Bis a schematic representation of sensors 414. Also shown is an actuatordevice 410 for positioning the permanent magnet. The magnetic damper andsensor package in shuttle carrier 204 includes a cylindrical shapepermanent magnet 402 that is polarized in the radial direction. Thepermanent magnet is reciprocably mounted in pole pieces 406 such that itcan reciprocably rotate about its cylindrical axis. The magnet positionas shown in FIG. 4A is representative of the magnetic damper on positionor the acoustic clamping position as shown by arrow 408. FIG. 4B shows amagnet position representative of the magnetic clamper off position orrelease position as shown by arrow 409. The magnetic damper is activatedwhen an actuator turns the permanent magnet 402 90 degrees from theposition shown in FIG. 4B to the position shown in FIG. 4A. When themagnetic damper is in the release position as shown in FIG. 4B, magneticflux 404 is redirect to be closed or contained in the pole piece 406 toprevent magnetic flux leakage. When the magnetic damper is in theclamped position as shown in FIG. 4A, magnetic flux 403 is redirected togo outside of the pole pieces such that the flux comes out of eitherpole piece and goes back through the casing to the other pole piecegenerating a strong clamping force. The clamping force is perpendicularto the casing as shown by arrow 408. The magnetic clamper, integral withthe sensor package 308, is lightweight making the effective clampingmass small. The actuator for rotating the cylindrical permanent magnet90 degrees is shown as a hydraulic actuator 410. The hydraulic line 412allows for remote actuation of the hydraulic actuator 410 adapted torotate the cylindrical magnet 90 degrees. The actuator 410 could beactuated by any other appropriate actuator means such as an electricalactuator or an electromechanical actuator and an appropriatecorresponding signal line would replace the hydraulic line. The samemagnetic sensor device discussed above can be utilized for the bowspring shuttles described in FIGS. 7 through 9.

Also shown in FIGS. 4A and 4B is a representation of a seismic sensor414. The seismic sensor is a device for sensing and converting seismicwaves into electro-optical signals. Examples of seismic sensors includehydrophones, geophones, fiber optic geophones, three-axis seismicsensors, or geophone accelerometers.

Referring to FIG. 5, a representative schematic of the downhole fiberoptic sensor with downhole calibration capability is shown. FIG. 5 showsa fiber optic communication fiber 502 communicably linked to an opticalelectronics converter 504 which is further communicably linked to thefiber optic seismic sensor 506 and the transducer 508 utilized forcalibration. Types of transducers include piezoelectric transducers andelectromagnetic transducers. One particular embodiment providespiezoelectric transducers. One embodiment of a calibration technique isshown where calibration can be performed without downhole power suppliesor other complicated downhole electronics. Downhole calibration isadvantageous to quantify the sensor response. The combination of anoptical electronics converter 504 and a transducer 508 allows thedownhole calibration of the fiber optic geophone to be performed in-situwith minimal downhole electronics. One method is to provide a lightsource through the optical fiber. The photo detectors of the fiber opticgeophone will produce the modulated photo current which will activatethe piezoelectric transducers. The transducers are acoustically coupledto the fiber optic geophones and excite the geophones as shakers.Calibration is allowed because of the known input signal and theexpected response. The same fiber optic communication line can be sharedfor both measurement and calibration signals. A further embodimentincludes providing a capacitor in communication with the transducers 508to provide energy for activating the transducers 508. One method tostore energy in the capacitor is to provide opti-electric converters inconjunction with the capacitors and to charge the capacitor with a lightprovided to the optical fiber

Referring to FIG. 6, a functional diagram of one embodiment of theborehole sensing apparatus 600 is shown. The apparatus 600 includes aplurality of shuttles 204 along the cable line 112 that contains asensor and damper package. Other sensors 602 can also be attached alongthe wireline such as the pressure/temperature (P/T) sensors shown inFIG. 6. The wire line 112 can be adapted to carry various communicationlines, including fiber optic sensor array communication lines for thefiber optic system. The wire line 112 can also be adapted to carry thehydraulic line or electrical line actuator control for actuation of themagnetic clamper. Also shown in FIG. 6 is a downhole battery 604 thatcan be utilized to support various power needs. Various monitoring andcontrol systems can be located at the surface such as the actuatorcontrol system 606 which can be operable to control actuation of themagnet clamp. The borehole sensor system 608 can monitor, store, andinterpret the data output by the sensors. Also, a P/T sensor system 610can be located at the surface and communicably linked to a downholesensor to monitor down-hole pressure and temperature. Still further, adistributed temperature sensor 616 is shown, which is communicablylinked to a distributed temperature sensor (DTS) system 612 forproviding a continuous temperature profile. Also, a cable lengthmeasurement system 614 such as an Optical Time Domain Reflectometer(OTDR) system as shown as the surface can be used. Electrical cartridge618 is shown on the conveyance below the sensor section. In a furtherembodiment, the borehole sensors are seismic sensors.

Referring to FIGS. 7, 7 a and 7 b, a tubing-conveying tool with a bowspring to shuttle interface is shown as an alternative embodiment. Thetubing tool 700 is shown comprising a coiled tubing 702 with a shuttle704 attached thereto by bow spring device 706. The shuttle can besimilarly configured as the shuttle described in FIGS. 2, 3, and 4including the magnet clamp and the sensor package. FIG. 7 illustratesthe position of the shuttle when the tension of the bow spring 706 isreleased, and when the shuttle is extended outward and away from thetubing. The bow spring 706 and shuttle 704 can held against the tubingFIGS. 7, 7 a and 7 b show how the shuttle can be used with a bow springmechanism that attaches the shuttle to the coiled tubing. When thecoiled tubing is deployed, the bow spring can be collapsed against thetubing. A protective mounting, cover, or other such device larger thanthe shuttle 704 can be provided to hold bow spring 706 against tubingduring deployment to protect shuttle 704 from damage during deployment.The magnets 708 attached to the exterior of the coiled tubing and theshuttle can be configured to magnetically attract each other to furtherhold the shuttle against the tubing. Once the desired depth has beenreached, the magnet on the sensor package can be activated via theactuator control line 712 to reverse its polarity such that the shuttlemoves away from the coiled tubing by combination of the opposingmagnetic forces and the release of the tension on the bow spring.Alternatively the magnet 708 on attached to the conveyance can beactivated via an actuator control line to reverse its polarity. Toretract the shuttle, the magnet can again be reversed. The forces of themagnets are such that they are greater than necessary to collapse thebow spring. FIG. 7 a depicts the bow spring in its collapsed positionsuch that the shuttle 704 is collapsed against the magnet 708. FIG. 7 bdepicts the tension of the bow spring being released thereby extendingthe shuttle outward and away from the tubing for coupling to theborehole casing 710. The bow spring configuration facilitates couplingof the shuttle to the borehole casing such that establishment of thecoupling relationship is not totally reliant on the magnet clamp.

Referring to FIGS. 8 and 8 a, a bow spring two-part shuttle for aconveyance is shown. The two-part shuttle 800 comprises an exteriorcradle shuttle portion 802 and a main sensor shuttle portion 804attached thereto by a bow spring mechanism 806. FIG. 8 shows thetwo-part shuttle with the bow spring collapsed inside the exteriorcradle shuttle portion such that the main sensor shuttle portion iscradled within the exterior cradle shuttle portion. The collapsing ofthe bow spring pushes the main sensor shuttle portion inside which isfurther facilitated by the attractive magnetic forces between themagnetic clamp 808 of the main sensor shuttle portion 804 and the magnet810 attached to the interior of the exterior cradle shuttle portion. Aguide 812 and slider 814 mechanism can further facilitate collapse ofthe bow spring. The exterior cradle shuttle portion can be attached to awire line and the main sensor shuttle portion can be extended orretracted by the bow spring in combination with the magnetic forces ofthe magnetic clamp 808 and magnet 810. The extension of the main sensorshuttle portion outward from the exterior cradle shuttle portion asshown in FIG. 8 a further facilitates coupling the shuttle to the borehole casing similar to the shuttle configuration shown in FIG. 7. Againthe bow spring facilitates coupling the shuttle to the borehole casing.

Referring to FIGS. 9 and 9 a, a shuttle embedded in a wire line having abow spring interface is shown. The two-part shuttle design shown inFIGS. 9 and 9 a has similar functionality to the shuttle shown in FIGS.8 and 8 a. However, for this embodiment, the shuttle is embedded in thewire line conveyance. The shuttle is embedded and fixed within theconveyance by the mold portion 902. The shuttle is further fixed andembedded within a cable by a stress core 904 and a swage 906. The cablejacket 908 has an outer diameter that is approximately the same as theshuttle device. The shuttle comprises an exterior cradle portion 910having a magnet 912 therein. The main sensor shuttle portion 914 of theshuttle is attached to the exterior cradle portion 910 by a bow springmechanism 916. FIG. 9 shows the bow spring in its collapsed positionsuch that the sensor package portion 914 of the shuttle is collapsedwithin and cradled within the exterior cradle portion 910. Collapsing ofthe bow spring 916 is facilitated by the attractive forces between themagnet 912 and the magnetic clamp contained within the main sensorpackage portion 914. FIG. 9 a shows the sensor package portion extendedoutward from the cradle portion of the shuttle to establish a couplinginterface between the shuttle and the borehole casing 920.

One embodiment of the borehole sensing apparatus of the presentinvention as a wire line system is shown in FIG. 10. FIG. 10 is a wireline system view showing the use of a fishing head for retracting astuck tool. The wire line system tool 1000 is shown comprising a maincable or conveyance 1002, a sensor section 1004, an active fishing head1006 and a main electronics and weight portion 1008. The sensor sectionof the tool has a smaller outer diameter than the active fishing head sothat an overshoot of a fishing head can run over the sensor section. Theshuttles having sensor packages are attached along the sensor section ofthe conveyance tool. The main electronics and weight portion 1008 canhave a larger overall diameter than the overshoot. The weight portion1008 can also have a protruding end to fit into the overshoot. Theprotruding end can also be magnetic to attract the overshoot. The activefishing head can optionally have a sensor to detect latching of theovershoot to determine the point where the tool is stuck. Alternatively,a sensor such as a tension meter can be installed in the fishing head oras another alternative a distributed tension measure wire can beinstalled in the sensor section of the conveyance for sensing tension inthe conveyance indicative of a lower portion of the tool, such as theelectronics and weight portion 1008, being stuck. A communication linecan be provided for transmitting this tension sensing data to thesurface. The wire line system tool can be designed such that the portionof the conveyance at the bottom of the sensor section has a weak pointso that it is possible to cut and retrieve the sensor section and thensubsequently fish the main electronics and weight later. This wire linesystem tool design enhances the capability of retracting the tool forreuse. If a tool gets stuck it is likely that the larger components ofthe conveyance will be the components to get stuck. Configuring theconveyance tool such that the larger main electronics and weight arepositioned below the sensor section and such that a weak point in theconveyance is positioned there between will allow the conveyance to becut by applying tension when the larger component is stuck. Once theconveyance is cut the sensor section can be retrieved while leaving thestuck component downhole to be fished later.

A further embodiment comprises providing at least one tension-sensingdevice on the conveyance at the surface. The tension determined in theconveyance at the weak point can be compared to the tension determinedin the conveyance at the surface. Such a comparison can indicate thatwhether the apparatus is stuck above or below the weak point and can beused in determining actions such as to fish or to break the conveyance.

Industrial Applicability

The present invention has applicability for both performing boreholesurveys for planning well bore drilling and production and formonitoring borehole data during actual well production. Such boreholesurveys include borehole seismic surveys and such monitoring of boreholedata includes temporary or permanent monitoring. One embodiment of thepresent invention comprises a plurality of the shuttles comprisingborehole sensor attached along a cable line and spooled down theborehole for permanent or temporary monitoring of seismic data. Theplurality of borehole sensor arrays of the present invention that areattached along the wire line enables the system to record simultaneousmulti-level acquisition seismic data. One embodiment of the presentinvention utilizes a plurality of these seismic sensor arrays eachhoused in a plurality of shuttles having acoustic isolation and magneticclamping capabilities One embodiment of the present invention utilizesfiber optic geophone technology. Fiber optic technology has the abilityto multiplex multiple channels at a high data rate, thereby satisfyingthe demand for acoustic and seismic imaging applications which require alarge sensor array with high data transmission capabilities. Use offiber optic technology in embodiments of the present invention alsoallows for a greater number of shuttles because of the smaller profile,lighter weight and the fact that no downhole electronics or power fromthe surface is required.

One embodiment of the present invention is operable to spool downhole awire line or coiled tubing conveyance having a plurality of shuttlesensor packages spaced along the cable. Shuttles can be optionallyembedded in the conveyance as shown in FIGS. 7 through 9. The sensorscan optionally all be attached in a conveyance sensor section as shownin FIG. 10. Below the sensor section the larger components can bepositioned such as main electronic units, battery units, and weights.Placing the larger components below the smaller diameter sensor sectionfacilitates fishing as shown in FIG. 10 of the sensor section. Asdiscussed above a weak point in the conveyance can be positioned betweenthe sensor section and the larger components such that if the largercomponents get stuck during retraction of the tool, the spoolingmechanism can apply sufficient tension to the conveyance such that theconveyance is cut at the weak point leaving the larger componentdownhole to be fished later.

One skilled in the art will appreciate that a method like the presentinvention is also attractive in the area of borehole logging because youcan use the borehole sensing apparatus and method of the presentinvention in conjunction with a downhole source, such as a acousticsource provided in a sonic tool, to detect response signals at distancesfurther from your source than would be achievable or practical with thereceivers contained within the tool that houses your source. It can beappreciated that using a sonic tool with a receiver array such as in thepresent invention to expand the capability of the acoustic dataacquisition system without the difficulties and costs involved inexpanding the sonic tool itself.

There has been described and illustrated herein various embodiments of adevice and apparatus in accordance with the present invention fordownhole seismic data recording. While particular embodiments of theinvention have been described, it is not intended that the invention belimited thereby. Therefore, it will be apparent to those skilled in theart that various changes and modifications may be made to the inventionas described without departing from the spirit and scope of the appendedclaims.

1-8. (canceled)
 9. The borehole sensing apparatus as recited in claim 41where said acoustic isolator comprises a fine wire suspension and asuspension spring.
 10. The borehole sensing apparatus as recited inclaim 36 where said sensor package further comprises a seismic sensorarray consisting of seismic sensors selected from hydrophone, geophone,three-axis seismic sensor, fiber optic seismic sensor or geophoneaccelerometer.
 11. The borehole sensing apparatus as recited in claim 10where the sensor array is a fiber optic geophone array.
 12. The boreholesensing apparatus as recited in claim 11 where said fiber optic geophoneseismic sensor array further comprises a transducer acoustically coupledthereto and said transducer is operable to excite said geophones asshakers responsive to a modulated photo current for downholecalibration.
 13. (canceled)
 14. The borehole sensing apparatus asrecited in claim 42 where said actuator is a hydraulic actuator and saidmagnet is a cylindrical shaped magnet polarized in a radial directionand rotatably mounted between pole pieces, said hydraulic actuator beingoperable to reciprocably rotate the cylindrical magnet about itscylindrical axis for selectively magnetically clamping said shuttleagainst the adjacent structure and for selectively unclamping.
 15. Theborehole sensing apparatus as recited in claim 42 where said actuator isan electrical actuator and said magnet is a cylindrical shaped magnetpolarized in a radial direction and rotatably mounted between polepieces, said electrical actuator being operable to reciprocally rotatethe cylindrical magnet about its cylindrical axis for selectivelymagnetically clamping said shuttle against the adjacent structure andfor selectively unclamping. 16-35. (canceled)
 36. A borehole sensingapparatus comprising: a shuttle attached to a conveyance for placing ina borehole to sense borehole data, said shuttle having a sensor packagetherein, said sensor package having a magnet clamp operable toselectively magnetically clamp the shuttle to an adjacent structure andselectively magnetically unclamp the shuttle from said adjacentstructure, wherein said conveyance is operable to spool the shuttledownhole into a borehole.
 37. The borehole sensing apparatus as recitedin claim 36 wherein said conveyance includes communication linescommunicably linked to the sensor package for communication of boreholedata to the surface.
 38. A borehole sensing apparatus as recited inclaim 36 wherein said magnet clamp is further operable to magneticallyclamp the sensor package to the shuttle for acoustically coupling thesensor package, the shuttle and the adjacent structure together.
 39. Theborehole sensing apparatus as recited in claim 36 wherein saidconveyance is a tubing conveyance and said shuttle is attached to theexterior of said tubing conveyance by a bow spring adapted toselectively extend said shuttle away from said tubing conveyance andretract against said tubing conveyance.
 40. The borehole sensingapparatus as recited in claim 36 wherein the shuttle further comprisesan exterior cradle portion attached to a main sensor shuttle by a bowspring such that collapsing of the bow spring retracts the sensorshuttle in the cradle and releasing the tension of the bow springextends the sensor shuttle outward away from the conveyance and cradle.41. The borehole sensing apparatus as recited in claim 36 where saidsensor package in said shuttle is suspended by an acoustic isolatorsystem disposed between said shuttle and said sensor package, operableto isolate said sensor package from propagations through the shuttle andconveyance.
 42. The borehole sensing apparatus as recited in claim 36where said magnet clamp comprises: a permanent magnet reciprocablymounted in said sensor package; and an actuator operable to reciprocablyreorient said permanent magnet where said reorientation reciprocablyclamps and unclamps the shuttle.
 43. The borehole sensing apparatus asrecited in claim 36 wherein said shuttle is attached to a conveyanceoperably attached to a spooling mechanism, said spool mechanism beingoperable to selectively lower said conveyance and shuttle attachedthereto downhole into a borehole and further operable to selectivelyretract said conveyance.
 44. The borehole sensing apparatus as recitedin claim 42 wherein said conveyance comprises: a sensor arraycommunication line communicably linked between said sensor package and aborehole sensor system for carrying borehole data sensed by the sensorpackage and transmitted uphole to the borehole sensor system; and anactuator control line communicably linked between said actuator and anactuator control system operable to control the actuator for controllingclamping and unclamping.
 45. A borehole sensing apparatus as recited inclaim 42 comprising a conveyance system tool having a sensor section andhaving a weak point in the conveyance below said sensor section forbreak away during retraction if tool is stuck below the weak point. 46.The borehole sensing apparatus as recited in claim 45 further comprisinga tension-sensing device operable to sense tension in the conveyance atthe weak point.
 47. The borehole sensing apparatus as recited in claim42 wherein said sensor section comprises at least one shuttle, andwherein said at least one shuttle is attached to a conveyance, furthercomprising an active fishing head attached to the conveyance below saidsensor section.
 48. The borehole sensing apparatus as recited in claim47 wherein the active fishing head further comprises a magnet.
 49. Theborehole sensing apparatus as recited in claim 47 wherein the activefishing head further comprises a sensor to detect latching of anovershoot. 50-67. (canceled)
 68. A method for sensing borehole datacomprising the steps of: deploying a shuttle in a borehole onconveyance, said shuttle comprising at least one sensor packagecommunicably linked to at least one sensor communication line fortransmitting borehole data uphole, said at least one sensor packagehaving a magnet clamp operable to magnetically clamp said at least onesensor package to an adjacent structure; providing a weak point in theconveyance below said sensor section; selectively spooling downhole saidshuttle attached to said conveyance, where said conveyance is attachedto a spooling mechanism; and selectively retracting uphole said shuttleusing said conveyance attached to said spooling mechanism.
 69. Themethod for sensing borehole data as recited in claim 68 furthercomprising sensing tension in the conveyance at the weak point with atension sensing device, wherein tension sensing device is communicablylinked to at least one communication line for transmitting tensionsensing data uphole.
 70. The method for sensing borehole data as recitedin claim 68 wherein said magnet clamp includes a permanent magnet and anactuator operatively attached to said permanent magnet, and operatingsaid actuator to reciprocally reorient said permanent magnet forclamping and unclamping said at least one shuttle.
 71. The method forsensing borehole data as recited in claim 70 further comprisingproviding an actuator control line integral with said conveyance andcommunicably linking said actuator and an actuator control system forcontrolling the actuation of said actuator for controlling clamping andunclamping; and further comprising operably attaching an acousticisolator between said at least one sensor package and said at least oneshuttle. 72-84. (canceled)
 85. A method for sensing borehole datacomprising the steps of: deploying a shuttle in a borehole onconveyance, said shuttle comprising at least one sensor packagecommunicably linked to at least one sensor communication line fortransmitting borehole data uphole; providing a weak point in theconveyance below said sensor section; selectively spooling downhole saidshuttle attached to said conveyance, where said conveyance is attachedto a spooling mechanism; determining tension in the conveyance at theweak point using a tension-sensing device; communicating determinedtension uphole; and selectively retracting uphole said shuttle usingsaid conveyance attached to said spooling mechanism.
 86. The method forsensing borehole data as recited in claim 85 further comprisingproviding a tension sensing device at the surface and determiningtension in the conveyance at the location of the tension sensing deviceat the surface; and comparing the tension in the conveyance at the weakpoint to the tension in the conveyance at the surface.
 87. The methodfor sensing borehole data as recited in claim 85 further comprisingcomparing the tension in the conveyance at the weak point to the tensionat the conveyance at the surface.